Field of Invention
The present invention relates to a hydraulic control apparatus for a hydraulic torque converter applicable to an automatic transmission for a vehicle. More particularly, the present invention relates to a hydraulic control apparatus for a hydraulic torque converter that can control a damper clutch mounted in the hydraulic torque converter in a similar way to controlling a start clutch.
Description of Related Art
A torque converter applied to a vehicle includes a damper clutch for directly and mechanically transmitting torque. The damper clutch is disposed between a front cover being an input-side rotation member of the torque converter and a turbine being an output-side rotation member of the torque converter. A space between the front cover and the turbine is divided into a disengagement-side oil chamber close to the front cover and an engagement-side oil chamber close to the turbine.
Therefore, whether the damper clutch is operated or not is controlled by the difference between hydraulic pressure of the disengagement-side oil chamber and hydraulic pressure of the engagement-side oil chamber.
That is, if fluid in the disengagement-side oil chamber is drained and fluid is supplied to the engagement-side oil chamber, the hydraulic pressure of the engagement-side oil chamber increases compared with the disengagement-side oil chamber. Therefore, a friction member of the damper clutch is coupled to the front cover by friction.
On the contrary, if fluid in the engagement-side oil chamber is drained and fluid is supplied to the disengagement-side oil chamber, the hydraulic pressure of the disengagement-side oil chamber increases compared with engagement-side oil chamber. Therefore, the friction member of the damper clutch is spaced from the friction cover.
Since engagement/disengagement is simply controlled according to a conventional damper clutch, temperature may rise and durability may be deteriorated if the damper clutch is controlled in similar way to controlling a start clutch where slip occurs frequently.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.